System of electric-motor control



Fins].

Aug. 1a, 1925.

1,550,186 E. B. TUPPEN SYSTEM OF ELECTRIC moron CONTROL Fil ed Jan. 16, 1924 I Inventor: Edward B.Tuppen,

His Attorney Patented Aug. 18, 1925.

UNITED STATESPATENT QFFICE.

EDWARD BROWNE TUPPEN; OF BIRMINGHAMI, ENGLAND, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SYSTEM OF ELECTRIC-lvIOTDR CONTROL. i

Application filed January 16, 1924. Serial No. 686,620.

To all whom it wmzy concern:

Be it known that I, Enwann BnowNE Tun run, a subject of the British Empire, residing at Birmingham, England, have invented certain new and useful Improvements in Systems oi? Electric-Motor Control, oi? which the following is a specification.

This invention relates to systems of electric motor control, and more particularly to such systems in which the mot-or accelerat ing contactors are closed in a definite sequence for controlling the starting resistance and the series parallel combinations oi the motors by means of cams mounted on a shaft which is driven by a pilot motor. In systems of this charac er it is usual for the motor reverser to he operated by solenoids, which have to be suiiicientiy powerful to throw the reverser with certainty even under adverse working conditions, such as low line voltage. This arrangement requires heavy and costly solenoids which consume comparatively large control currents.

The object of the present invention is to provide simple and eiticient means for operating the reverser, whereby the use of heavy and costly solenoids will be avoided and to that end it consists in arranging the reverser so as to be operated by the pilot motor which drives the cam shaft for the ac celerating cont-actors.

In one method of carrying out the invention, additional cams are mounted on the cam shaft so as to make use of the cam shaft mechanism during its initial angular move ment from the 01? position for operating; the reverser. It is arranged so that if the reverser is already thrown in the desired direction, it will be left in that position and will not in any way be affected by the movement or the cam shatt. if, however, the reverser is not. in the desired position, it will be operated to this position during the initial movement of the cam shaft. Obviously, it is desirable that the initial angular movement oi. the cam shaft necessary to operate the reverser be reduced to a minimum, but the minimum angular movement is limited by the force required to operate the reverser,

as anunduly large force would be required if the movementallowed is too small. T he cams are so formed that the reverser will be held in the respective forward or reverse position without any load on the cam shaft once the reverser is fully thrown to these positions.

in place oi the usual solenoids ior operating the reverser, two comparatively small solenoids are employed by setting; the cam mechanism previous to the movement of the cam shaft, so that the reverser will be thrown to the desired position. It will be understood that this preliminary setting of the cam mechanism can, by means of suitable contacts, he made to reduce the current in the operating solenoids or even open the solenoid circuit completely alter the mechanism is set a. cording to the scheme of connections adopted. Provision may be made for reducing the current in the solenoids by means of suitably arranged contacts which transfer the coils to a retaining circuit containing other coils or resistances.

One method of carrying the invention into efiect illustrated in the accompany ing drawino's, in which 1 is a schematic diagram or the cam-operated reverser and its tonnectionm l io. 2 is a detail view of the cam mechanism, and l 2-3 is an arrangement in which the cam-operated reverser is incorporated with a cam-operated type of line breaker.

Referring to Figs. 1 and 2, the switch 1 is arranged to control the energization of the two solenoids 2, A lever l of magnetic material is provided with the projections 0, 6, which are adapted to be attracted by the solenoids 2, 3 respectively. A member 7 is mounted on the shaft 12, wiich is squared or otherwise formed so that the member 7 is tree to slide axially upon it, but is bound to rotate with it. Two rollers 8, 9 are arried by the member 7 and are adapted, respectively, to engage with cams 10, 11 according to the position of the member 7 on the shaft 1 A reverser 13 of any known type is mounted on, or driven by, the shaft 12, and cooperates with a set of contacts i l comprisino segments 15, which is adapter. to be moved by the lever 4. The cams 3.0, 11 are rigidly secured to a cam shaft lo, which is driven by a pilot motor (not shown) and may also carry suitable cams 16 for operating; switches 1.6" and ZMXZQlQYtatiD g1 contactors 16" for the motor hi: indicated in the drawing.

.Vhen the lever at is attracted by the solenoid 3, the member 7 is moved to the right,

the roller 9 is brought into line with the cam 11, and the roller 8 is moved out of line with the cam 10. Similarly when the lever 1 is attraLted by the solenoid 2, the member 7 is moved to the left, the roller 8 approaches the cam 10, and the roller 9 moves away from the cam 11.

The cam shaft 16 has a definite off position and when in this position both the rollers 8, 9 are clear of the operating surfaces of the cams 10, 11, thus readily allowing the member 7 to be operated to either of the two positions referred to above. The cam shaft 16 is shown in the off position in Fig. 2 and revolves in a clockwise direction for starting up the motor.

In order to prevent any possibility of the lever 41 being operated at any position of the cam shaft other than the off position, interlock switches 22 and 23" may be pro vided, and arranged to be operated by some moving Pt rt on shaft 16 so that, once opened, they cannot be closed, except by the return of the cam shaft 16 to the off posi tion.

The relative positions of the cams 10, 11 and the rollers 8, 9 may be arranged as indicated, so that the member 7 cannot move axially except when the cam shaft 16 is at or near the oil posit-ion, thus providing a mechanical interlock which prevents incorrect operation. For example, if the cam shaft 16 has been rotated away from the position shown in Fig. 2, the bifurcated arm of member 7 which carries roller 9 will come against the left-hand side of the cam 11 and thus prevent sufficient movement for the roller 8 to come out of line with the cam 11.

The operation of the system is as follows: Assuming that it is desired to move the reverser 13 to the reverse position from that shown in Fig. 2, the switch 1 is moved to the right, energizing the solenoid 6 and moving the lever at and the member 7 to the right. The roller 9 then comes in line with the cam 11, the roller 8 moves away from the cam 10, and the switch contacts 15 are moved to the right. Before the contacts 15 are moved, the energizing circuit for the solenoid 3 is from the positive terminal through contacts 21, 22, 22 solenoid 3, con tacts 18, 17, 24 and resistance 27 to ground. After the contacts 15 are moved, this circuit is from the positive terminal through contacts 21, 22, 22, solenoid 3, contacts 18, 19, Winding 25, resistance 26, to ground. The roller 9 now being in line with the cam 11, rotation of the cam shaft 16 in a clockwise direction by the pilot motor causes the member 7 to be moved in a counter-clockwise direction and the roller 8, which is now out of line with the cam 10, moves in towards the shaft 16. The cam 1.1 lifts the roller 9 to its outer diameter and retains it in that position while the cam shaft 16 is being further operated by the pilot motor to any starting or running position.

The cams 16, 11 are shown, in Fig. 2, in the position corresponding to the off position, and as the circuits of the solenoids 2, 3 are interlocked by the contacts 22 and 23 so that the lever 1 cannot be operated except with the cam shaft 16 in the off position, the movement of the member 7 along the shaft 12 will not be prevented by either of the rollers 8, 9 coming into contact with the side of either of the cams 10, 11, as the relative positions of the rollers and cams will be as shown in Fig. 2. From Fig. 2 it will. be seen that the roller 8 and the cam 10, which are in line with each other, have their working faces well out of engagement, and the roller Q) and cam 11 have a good working clearance, which will allow them to come into line without risk of interference.

It has been assumed in the operation just described that the reverser 13 is not in the position required, so that the switch 1 has to be moved to set the reverser 13 in the desired position by means of the solenoid 3, but the revcrscr 13 as shown may already be in the desired position, in which case the switch 1 is moved to the left, unless it had previously been left in that position. The movement of the switch 1 to the left enerthe solenoid 2, but the lever 1 and the switch contacts 15 remain stationary since they are shown as in the left-hand position. The ener izing circuitfor solenoid 2 will then be from the positive terminal through contacts 21, 23, 26, solenoid 2, contacts 20, 19, winding 25, resistance 26, to ground. In this case it will be seen that clockwise rotation of the cam shaft 16 by the pilot motor will not operate the lever 7 as the roller 8 is already in a position corresponding to the outer diameter of the cam 10, although it will not actually come into contact with the cam 10 until the cam shaft 16 has rotated a certain amount.

Fig. 3 illustrates the can'i-operated reverser incorporated with the cam-operated contactor type of line breaker described in the copending application of Hammond C. Hastings, Serial No. 674,585, filed November 13, 1923, and assigned to the assignee of my present invention. As more fully set forth in the Hastings application, the circuit breaker 28 is arranged to be mechanically closed by the cam shaft 16 and is restrained in its closed position by a shunt coil 28". The breaker 28 is mechanically connected to a switch 28, which closes when the breaker 28 closes. A line contactor 29, also operated by the cam shaft 16, is in the main circuit of the motor 30 and closes after the cam on cam shaft 16, which closes the breaker 28, is moved past.- its operative position. An overload relay 31 with contacts 31 and 31 and a resetting coil 31, and a no-voltage relay 82 with contacts 32 and 32 are also provided. An auxiliary relay 33 controls the direction of rotation of the pilot motor which drives the cam shaft 16. Relay 83 carries contacts 34 and 3% adapted to open the circuit of the cam shaft motor 35 at the full on and off positions. A master controller 36 is provided with a control switch 37.

The forward and reverse contacts 1, the solenoids 2, 5, interlocks 22* and 23 and the contacts 15 of the oamoperated reverser are also shown in Fig. 3. The circuit for the auxiliary relay 33 passes from one of the reverse contacts 1 of the master con troller 36 through a corresponding one of the interlocking contacts 22 or 23 and the corresponding coil 2 or 3, contacts 15, switch 28*, contacts 31 and 32 to the coil of relay This prevents the pilot motor 35 from advancing cam shaft 16 from the off position shown in Figs. 1 and 2 until the reverscr 18 first has been moved to the correct position for forward or reverse running as previously described.

The winding 25 and the resistance 26, shown in Fig. 1, may be replaced by a resistance only, or by solenoids such as the line breaker retaining solenoid 28 Fig. 3.

While only one method of carrying the invention into eli'ect has been described, it is obvious that various modifications may be introduced without departing from th spirit of the invention.

lVhat I claim as new and desire to secure by Letters Patent of the United States, is,

1. In a motor control system, the combination with the motor accelerating switches, of a reverser, a cam shaft adapted to operate the accelerating switches for the motor, and an electrically actuated mecha nism for connecting the reverser for mechanical operation by said cam shaft.

2. In a motor control system, the combination with the motor accelerating switches, of a reverser, a cam shaft adapted to operate the said accelerating switches, and means for connecting the said reverser for mechanical operation by said cam shaft comprising an electromagnetically actuated member selectively operable into engagementwith a plurality of cams on the said cam shaft for determining the direction in which the reverser will be operated upon operation of the cam shaft.

In a motor control system, the combination with the motor accelerating switches, of reversing switch mechanism for the motor, a cam shaft adapted to operate the said accelerating switches, means for connecting the said reversing switch mechanism for mechanical operation by the said cam shaft comprising an electrically actnated member selectively operable into engagement with a plurality of cams on the said cam shaft for determining the direction in which the cam shaft will operate the rrcrser, and switch mechanism controlled by said cam shaft for preventing actuation of the said member after the said cam shaft is moved from the oil position.

a. In a motor control system, the combination with switch mechanism operable to connect the motor to a source of supply for operation in either direction, of accelerating switches for the motor, a cam shaft for operating the motor accelerating switches, and electrically actuated mechanism for establishing a mechanical driving connection between the said cam shaft and the said switch mechanism whereby the initial rotation of the former operates the latter.

In witness whereof, I have hereunto set my hand this twenty eighth day of December, 1928.

EDWVARD BROVJNE TUPPEN. 

